1. Technical Field
The invention relates to an oscillator configured by mounting a resonator and an oscillation circuit in a package. Further, the invention relates to an electronic apparatus, a moving object, and so on using such an oscillator.
2. Related Art
In some cases, for example, a quartz crystal oscillator is configured by mounting a quartz crystal resonator and a semiconductor device (IC) in a package. In such a quartz crystal oscillator, in some cases, the characteristic of the quartz crystal resonator is improved by overdriving the quartz crystal resonator, or the quartz crystal resonator is connected to an external measurement device to check the characteristic prior to mounting the IC using two monitor terminals connected to the quartz crystal resonator. Therefore, in general, the wiring pattern for connecting the quartz crystal resonator and the monitor terminals is elongated, and becomes easy to be affected by an external noise such as a noise from a digital circuit. As a result, there is a problem that the oscillation frequency is shifted from a preset value, or a phase distortion is generated.
As a related-art technology, in JP-A-2012-186784 (paragraphs 0021-0022, FIG. 1) (Document 1), there is disclosed a quartz crystal oscillation device having a semiconductor package and a quartz crystal resonator mounted on a wiring board. The semiconductor package is provided with a first external terminal and a second external terminal used for connecting the quartz crystal resonator. On the wiring board, there are formed a first wiring pattern extending from the first external terminal and connected to one end of the quartz crystal resonator, and a second wiring pattern extending from the second external terminal in roughly the same direction as the first wiring pattern and connected to the other end of the quartz crystal resonator.
Further, on the wiring board, there is formed a third wiring pattern disposed in an area between the first wiring pattern and the second wiring pattern, and electrically connected to a ground power supply voltage. Thus, it becomes possible to reduce the pin-to-pin parasitic capacitance between the first external terminal and the second external terminal, and to reduce the pin-to-pin coupling noise. As a result, it is possible to satisfy the requirement of reduction of the parasitic capacitance and improvement of noise immunity.
Further, JP-A-2006-54269 (paragraphs 0001-0005, FIG. 1) (Document 2) discloses a piezoelectric oscillator configured by combining an IC having the oscillation circuit, the temperature compensation circuit, the memory circuit, and so on integrated with each other and a piezoelectric resonator with each other. This piezoelectric oscillator is characterized in that a first analog circuit block including a temperature compensation circuit, a second analog circuit block including an oscillation circuit, and a digital circuit block including a memory circuit are integrated into a piezoelectric oscillator IC, and in the piezoelectric oscillator IC, the first analog circuit block and the second analog circuit block are disposed separately from each other, and the digital circuit block is disposed so as to intervene between these analog circuit blocks.
In this piezoelectric oscillator, the digital circuit is used only for writing data to the memory in an adjustment operation in the factory when producing a TCXO, and there is no chance to operate the digital circuit in the state in which the piezoelectric oscillator is used as the TCXO. Therefore, the object is to prevent the malfunction of the piezoelectric oscillator caused by interference between an AC circuit block and a DC circuit block in the analog circuit. An example of the interference is as follows. An AC operation of the oscillation circuit causes a noise in the DC circuit, and thus, the phase noise, which is an important characteristic of the quartz crystal oscillator, is affected.
Document 1 discloses the improvement of the noise immunity of the first external terminal and the second external terminal to be connected to the quartz crystal resonator, but does not particularly disclose the improvement of the noise immunity of other terminals. Further, unlike the piezoelectric oscillator disclosed in Document 2, in such an oscillator as a digitally controlled crystal oscillator (DCXO) in which the oscillation frequency is dynamically digitally controlled during an oscillation operation, a digital control signal interferes an analog oscillation signal to affect the phase noise characteristic, and thus, the oscillation accuracy is deteriorated.